Silesaurus

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Silesaurus
Temporal range: Late Triassic, 230 Ma
Silesaurus szkielet.JPG
Reconstructed skeleton
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauriformes
Clade: Dracohors
Clade: Silesauridae
Genus: Silesaurus
Dzik, 2003
Species
  • S. opolensis Dzik, 2003 (type)

Silesaurus is a genus of silesaurid dinosauriform from the Late Triassic, approximately 230 million years ago in the Carnian faunal stage of what is now Poland.

Fossilized remains of Silesaurus have been found in the Keuper Claystone in Krasiejów near Opole, Silesia, Poland, which is also the origin of its name.[1] The type species, Silesaurus opolensis, was described by Jerzy Dzik in 2003. It is known from some 20 skeletons, making it one of the best-represented of the early dinosauriformes.

Description[edit]

Size compared to a human

Silesaurus measured approximately 2.3 meters (7.5 feet) long, and was facultatively bipedal. It was light and built for speed.

Silesaurus was an herbivore. The teeth were small, conical, and serrated. The tip of the dentary has no teeth, and some paleontologists think that it may have been covered by a beak.

Classification[edit]

S. opolensis restored without feather-like filaments
Silesaurus opolensis and Polonosuchus silesiacus models in Poland

Scientists think that Silesaurus was not a dinosaur, but rather a dinosauriform. Dinosaurian features lacking in Silesaurus include an enlarged deltopectoral crest (a muscle attachment on the humerus), and epipophyses (enlarged tendon attachment above the postzygapophysis) on the cervical vertebrae.

However, Silesaurus has some dinosaurian characteristics as well:

As a result, alternative hypotheses place Silesaurus at or near the base of the ornithischian dinosaurs. Other scientists propose a basal link between the basal sauropodomorphs and ornithischians.[1]

Systematic position after Nesbitt (2011):[2]

Ornithodira 
 Pterosauromorpha 

Scleromochlus

Pterosauria

 Dinosauromorpha 
 Lagerpetonidae 

Lagerpeton

Dromomeron

 Dinosauriformes 

Marasuchus

 Silesauridae 

Lewisuchus/Pseudolagosuchus

Asilisaurus

Eucoelophysis

Sacisaurus

Silesaurus

 Dinosauria 
 Saurischia 

Theropoda

Sauropodomorpha

Ornithischia

References[edit]

  1. ^ a b Dzik, J. (2003). "A beaked herbivorous archosaur with dinosaur affinities from the early Late Triassic of Poland." Journal of Vertebrate Paleontology, 23(3): 556-574.
  2. ^ Nesbitt, 2011. The early evolution of archosaurs: Relationships and the origin of major clades. Bulletin of the American Museum of Natural History. 352, 292 pp.